1. Field of the Invention
The present invention relates to a mounting system and a mounting method to be applied to fabricating flat panel displays, typically, liquid crystal panels. More particularly, the present invention relates to a component identifying apparatus for identifying the type and lying position (feed position) of an electronic component to be mounted on a substrate.
2. Description of the Related Art
Generally, mounting systems that mount electronic components formed in films (hereinafter referred to as “film electronic components”) on a glass substrate are employed in fabricating flat panel displays, such as liquid crystal displays. Such a mounting system, for example, includes a film electronic component feed device, a bonding member applying device, a bonding device, a substrate handling device and a substrate carrying device for carrying substrates between those devices. In the mounting system, the film electronic component feed device feeds a film electronic component. Then, the bonding member applying device applies an anisotropic conductive film (ACF) to the leads of the film electronic component, and the film electronic component is transferred to the bonding device. A glass substrate fed by the substrate handling device is set in place on the bonding device by the substrate carrying device. The displacement of the film electronic component relative to the glass substrate is detected by using a camera, the position of the film electronic component relative to the glass substrate is corrected, and the leads of the film electronic component is bonded to electrodes formed on the glass substrate through the ACF using a thermo compression bonding tool. After the film electronic v component has been thus mounted on the glass substrate, the substrate handling device transfers the glass substrate to the next processing station, and carries a new glass substrate to the bonding device.
Generally, the mounting system needs to mount film electronic components of a plurality of different types greatly differing from each other in size, mass and the like on a glass substrate.
Accordingly, it often occurs, when feeding a film electronic component to the mounting system, that a wrong film electronic component is fed or a film electronic component is fed in a wrong lying position and, consequently, the yield of product is liable to be reduced.
A component identifying method proposed to solve such problems determines whether a film electronic component to be mounted on a glass substrate is a correct one on the basis of the external shape of the film electronic component. FIG. 4 shows a component identifying apparatus for carrying out this component identifying method. As shown in FIG. 4, the component identifying apparatus is provided with a sensing unit 20 having a plurality of sensors 21 arranged in rows and columns. The external shape of a film electronic component 10 is estimated from detection signals provided by the sensors 21 to determine whether or not the film electronic component 10 is a desired one to be mounted on a glass substrate.
Since this known component identifying apparatus identifies the film electronic component 10 by its external shape, the known component identifying apparatus is unable to discriminate film electronic components 10 having similar external shapes stably from each other.
The positions of the sensors 21 of the known component identifying apparatus must be finely adjusted according to the external shape of the film electronic component 10. Therefore, when the known component identifying apparatus is applied to mounting film electronic components 10 of a plurality of different types on a substrate, the work for adjusting the positions of the sensors 21 takes much time.
Although the known component identifying apparatus does not have any particular difficulty in correctly identifying an asymmetrical film electronic component 10 as shown in FIG. 5A, the known component identifying apparatus mistakenly decides that a desired film electronic component 10 is fed correctly, in spite of being fed with the wrong side of the film electronic component 10 being faced up, when the film electronic component 10 is an axisymmetrical one as shown in FIG. 5B.